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Geoff Vallis

Professor Geoff Vallis

Professor Geoff Vallis

Research Fellow

Interests and expertise (Subject groups)

Grants awarded

Geophysical Fluid Dynamics and Climate

Scheme: Wolfson Research Merit Awards

Organisation: University of Exeter

Dates: May 2014-Apr 2019

Value: £50,000

Summary: My research is in climate and it is motivated by three questions. 1. What processes determine the overall state of Earth's climate? 2. How might the climate change in the future and how might it have changed in the past? 3. How does Earth's atmosphere compare with the atmospheres of other planets? Greenhouse gases are gases such as carbon dioxide that trap the radiation emitted from Earth's surface and so warm the surface. Although the warming effect is virtually certain, it is not known what other effects will arise, such as changes in regional climate or weather. My research proceeds on two, frequently intersecting, tracks. On one track we use complicated computer models that try to simulate all the important processes that determine climate. These models utilize the world's largest computers to solve the known laws of physics and chemistry on a three-dimensional grid covering Earth's atmosphere, ocean and land. Yet the models have two shortcomings. First, it is impossible to include everything, so that we have at times to make empirical or even arbitrary choices as to how to deal with some small but important phenomenon, like a cloud. Second, the models are enormously complex and simply and trying understand the models (never mind the real climate system!) is very difficult. Because the system is so complex, small changes can have large and unforeseen effects --- just like a small accident on the road can cause traffic backups for miles. The other track to my research is to try to strip the system to its bare essentials, to construct models that display the essence of a phenomenon with no extraneous detail at all. These can help us understand the system better and, of practical benefit, improve the sophisticated models we use to predict weather and climate. The benefit to society lies in being able to better predict the weather and climate as the planet warms, and to know the uncertainty of these predictions, and whether there is room for improvemen

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